VO2 max, O2 and CO2 transport, AcidBase Balance

imissyou419's version from 2017-02-02 01:46


Question Answer
VO2volume of O2 that body utilizes per min (while breathing room air)
VO2maxmaximum volume of O2 that the body can utilize per min (while breathing room air); higher VO2 max = higher aerobic fitness
What are the 3 factors that influence Vmax?1. cardiovascular system "get blood there",
2. muscle "oxygen utilization"
3. respiratory system "get oxygen in the blood" (cardiovascular system and muscle are the limiting factors so important for training to increase VO2max and respiratory system important for measurement of VO2max)
As you increase intensity of exercise, what happens to VO2?VO2 increases linearly until it plateaus to VO2max (that is when you start using anaerobic methods to create energy b/c hit maximum volume of O2 that the body can utilize)
What are the 2 ways O2 is transported?1. dissolved gas, 2. bound to hemoglobin
O2 as a dissolved gasminor component of O2 transport because O2 is not very soluble in blood so not adequate to meet tissue demands
O2 bound to hemoglobinmajor component of O2 transport
Structure of hemoglobinprotein consisting of 4 subunits, each subunit can bind 1 O2 molecule (each Hb can bind 4 O2 molecules)
3 Important features of Oxygen-hemoglobin dissociation curve1. PO2 in the lung is ~100 mHg, O2 saturation = 97%.
2. Due to sigmoid shape, small drop in alveolar PO2 will still allow an adequate Hb saturation.
3. steep portion of dissociation curve allow peripheral tissue to extract large amounts of O2 with relatively small drop in PO2
Sigmoid shape of hemoglobin-O2 dissociation curveallows for loading of O2 in the lung and unloading in peripheral tissue, is due to the binding characteristics of O2 to hemoglobin (binding of 1st O2 on a subunit increases the affinity of other subunits to O2)
4 factors influencing the oxygen-hemoglobin dissociation curve (shift it)↑ PCO2, ↑ temp, ↓pH or ↑ [H+] "lactic acid", ↑ DPG (metabolic product of RBC, increases in hypoxia) ALL SHIFT RIGHT (= PROMOTE OXYGEN UNLOADING AT THAT PO2)
What are the 3 ways CO2 is transported?1. as a dissolved gas, 2. as bicarbonate, 3. bound to hemoglobin
CO2 as a dissolved gas KNOW THISsoluble CO2 is 10% of CO2 transport because CO2 is more soluble in blood than O2
CO2 as bicarbonate KNOW THISHCO3- is 70% of CO2 transport;
bicarbonate is formed in the RBC and involves enzyme Carbonic anhydrase, after HCO3- is formed, it can diffuse into the plasma, Cl- will diffuse into RBC to maintain electron neutrality. H+ ions remain within RBC
How is bicarbonate formed?CO2 diffuse into RBC and Carbonic anhydrase converts it to H2CO3 (spontaneously becomes HCO3-), HCO3- can diffuse into the plasma, Cl- will diffuse into RBC to maintain electron neutrality. H+ ions remain within RBC
CO2 bound to hemoglobin, explain haldane effect KNOW THIS20% of transport
[H+] bind to deoxygenated Hb for HHb, CO2 binds HHB to form Carbamino-Hb so unloading of O2 in tissue enhances ability to transport CO2 - haldane effect
What does carbonic anhydrase do?H2O + CO2 -> H2CO3 (which then spontaneously become HCO3- and H+)
What maintains blood pH?buffer systems: reduce variations, lung (ventilation): affect HCO3- system, kidneys: (excretion/retention of acids/bases; important for life
Buffer (3 characteristics)1. a substance that can reversibly bind H+ ions so limits changes in pH i.e. if you add acid, does not change pH as much,
2. in the blood: bicarbonate system, protein system, phosphate system.
3. rapid
Respiratory acidosisreduced alveolar ventilation (e.g. "drugs", diseases) -> ↑ PCO2 "don't breathe out all air in lung so don't get rid of CO2" therefore ↓ pH/↑[H+] and ↑[HCO3-]
Respiratory alkalosisincreased ventilation (e.g. high altitude) -> ↓ PCO2 "increase ventilation b/c of PO2 drop at high altitude so get rid of more PCO2" results in ↑pH/↓[H+], ↓[HCO3-]
Role of kidneysexcretion of acids/bases so impact on [HCO3-], slower effect than those of buffer system and lung
Metabolic acidosisuncontrolled diabetes (production of acids/ketones) -> Low [HCO3-] or ↓pH/↑[H+]
Metabolic alkalosisdiuretic use -> High [HCO3-] or ↑pH/↓[H+]
Respiratory acidosis metabolic compensation by kidneysRespiratory acidosis results in ↑PCO2 so ↓pH and ↑[HCO3-]; metabolic compensation by kidneys to ↑[HCO3-] and so ↑pH

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